Is your feature request related to a problem? Please describe.
As for right now, there doesn't to be any type definition for webhook events inside this library that will help validate the incoming webhook events.

Describe the solution you'd like
It'd be great to have a built-in type definition for webhook events in this library. This will save us time of having to manually write our own.

Describe alternatives you've considered
What i've been doing so far is to model the types of each events(charge.success as for now) based on received webhook response or often time cross check supported-events

Additional context
None